The Neuropathology Core will use morphometric immunocytochemical and histochemical methods to confirm the severity and distribution of the lesions produced in animals which have experienced cerebral ischemia as a part of Projects 1-4. The histological analysis carried out in the Neuropathology Core will provide the essential information for correlating lesions, clinical signs, and physiological data. The Neuropathology Core will use these same specimens to define the chemoarchitectural similarities and differences among animals of different ages and species to identify common factors which might account for the selective vulnerability of certain brain regions to ischemia.